Safety mechanism for cranes



June 21, 1932. w j KEENAN ET AL 1,863,63fi

SAFETY MECHANISM FOR CRANES Filed July 1, 1950 INVEN-I-U RS:

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Before explaining in detail'the present in- Patented June 21, 1932 UNITED 's'ra'ras PATENT oFFIcE.

WILLIAM-J. KEENAN AND GUERCDON SATHER, OF DETROIT, MICHIGAN, ASSIGNORS TO HUDSON MOTOR CAR COMPANY, 035 DETROIT, ,MICI-IIGAN, A CORPORATION OF MICHIGAN SAFETY MECHANISM FOR CRANES Application filed July 1,

This invention relates to crane installations and more particularly to safety mechanism for stopping the cranes to prevent collision. In factories-where travelling cranes are em a ployed for conveying difi'erent objects from various points to a common place for assembly together, collision between two cranes often occurs. It is an object of the present invention to provide a safety mechanism for cranes which will render their operating mechanism inoperative and bring them to a stop when they have been moved toward one another to predetermined relative positions and thereby prevent their collision.

"vention, it is to be understood that the invention is not limited in its application to the details of construction and arrangement of parts illustrated in the accompanying drawing, since the invention is capable of other embodiments and of being practised or carried out in various ways. Also it is to be understood that the phraseology or terminology employed hereinis for the purpose'of description and not of limitation, and it is not intended to limit the invention beyond the terms of the several claims hereto appended as considered in View of the prior art and the requirements thereof.

The invention will be more clearly understood from the following description in conjunction with the accompanying drawing, in

' which:

Fig. l is a plan view of a portion of a crane installation embodying the invention, and

J5 igs. 2 and 3 are diagrams illustrating the operation of the safety mechanism.

The crane installation embodyingthe in vention may comprise cranes l0 and 11 supported for movement along parallel tracks 12 (only one of which is shown in Fig. 1) by wheels 13 mounted upon axles 14 rotatably mounted in the frame of the cranes. Each of the cranes l0 and 11 is provided with suitable mechanism for moving them toward and away from one another along the rails 12.

.This mechanism may comprise a motor mounted upon the frame of each crane and r 7 having an armature shaft carr in a Jinion 21 adapted to engage a gear 22 mounted upon 1930. 7 Serial No. 465,236.

a shaft 23 which is rotatably mounted in the frame of the crane. The shaft 23 is provided at its ends with a pinion 24 adapted to engage a gear 25 mounted upon the end of one of the wheel axles 14. v

In the form illustrated, the mechanismfor driving the cranes is supplied with electrical power from a switch which is connected with suitable feed lines 31. Leads 32 and 33 are connected between the switch 30 and T- rails 34 and 35, respectively. Contact shoes 36 and 37 are mounted to move with the crane 10 and are adapted for engagement with the T-rails 34 and 35, respectively. These shoes are connected by leads 38 and 39 with the terminals-4O and 41'whic-h are adapted to be engaged by the arms 42 and 43 of a switch.

' The arm 42 is connected by a lead 45 with a switch 46jof an auxiliary contactor A and the arm 43 is connected by a lead 47 withthe motor 20. The other terminal of the motor is connected by a lead 48 with a contact shoe 50 movable with crane 10 and adapted to engage a T-rail 51. A lead 52 connects the switch 46 with the lead 48. A lead 4 connects the coils 5 of the auxiliary contactorA and a switch 6 of a controlling relay which is connected by a lead 4 with the lead 47. The

other side of the coil 5 is connected with the lead 45 by a lead 9. A contact shoe carried by the crane 11 is adaptedfor engagement with the T-rail 51 and is connected by a lead 61' with one terminal ofthemotor 20 on the crane 11. The other terminal of this motor is connected by a lead 62with a contact shoe 63 carried by the crane 11 and adapted forengagement with the T-rail 35. Each of the motors 20 is connected by leads 59 to the controller for the respective cranes.

In accordance with the invention, a con trol circuit is provided which includeselectrically actuated mechanism for rendering the crane-operating means inoperative and which is so arranged that its'resistance is varied in response to the relative movement of the adjacent cranes to decrease the energy supplied to the mechanism so as'to render it inoperative andthus render the crane-operating means inoperative. One form ofcontrol circuit may comprise a conductor 65arand 70 move along the conductor65 thus de jcreasmg or ncreasing relatively, depending ranged for engagement by a contact shoe 66 carried by the crane and connected by a lead 67 with a coil 8 of the controlling relay 'C which, when energized, maintains the switch 6 thereof closed. When the coil 8 is deenergized. the switch 6 is opened by a. spring 7. The coil 8 is grounded through a lead 69. A contact shoe 70 carried by crane 11 is adapted for engagement with the conductor and is grounded through leads 71 and 72; Thus, the contact shoes 66 and form part of two separate circuits which are connected in parallel to the conductor 65 of the control circuit, each of these parallel circuits being grounded respectively through leads 69 and 72 and completed through the track 12 which is grounded as at 73 and 7%.

The control circuit is supplied with power from a generator 75 which is, connected through the leads 77 and 78 tothe conductor 65 and track 12 respectively. "The power supplied to the control circuit is controlled by a suitable current limiting resistance 76.

In operation the cranes 10 and 11 are lmoved along the tracks 12 towards and awa from-each other by power supplied throug the leads 31. At the same time energy is supplied to the control circuit'by the generator 75 and this energy is limitedby the resist- F .ance 76thus'maintainingthe energy supp-lied .constant. As the cranes are moved relatively along the tracks 12, the contact shoes 66 upon-the direction of travel, the'resistance of :the parallel circuits connected thereto. The arrangement is such that when the cranes .7 10 and '11 have moved to a predetermined position apart, the relative'resistance of the i circuits connected in parallel is varied to ,such an extent as to decrease the energy pass ing through the coil 8 thus permitting the switch -6to be opened mechanically by the pring 7 to shut off the-power supplied for operating the cranes.

The operation of the control circuit will be best-understood by reference to'Figs.-2 and 3 wherein the resistance of the parallel circuits carried inpartby the cranes 10 and 11 are designated as R and R respectively. If

weiassume as illustrated in Fig. 2, that the crane 10 remains stationary while the crane 11 ismoved from'the full-line position to the dotted-line'position a] distance mto bring .the cranes to their relative stop positions, the resistance R is diminished bythe amount ofresistance of an m length of the conductor 65 while theresistance R remainsthe same. As

a result, the current passing through the parallel circuit carried in part by the crane 11 is greatly increased passing through the .parallel circuit carried in part by crane 10 is diminished so as to deenergize the coil 8 and permit the switch '6 to. open. On the other hand, as illustrated in Fig. 3,, if the .the assembly line, while crane 11 remains stationary and the crane 10 is moved a distance X to bring it to its closest desired position relative to crane 11, the resistance R is increased by an amount equal to the resistance of an :1: length of the conductor 65 while the resistance R remains the same. As a result the major portion of the current supplied to the conrol circuit passes through the parallel circuit carried by the crane 11 and the current passing through the circuit carried by the crane 10 is reduced to such an extent as to de-energize the coil '8 and permit the switch 6 to open. It will be clear from the above explanation that if the cranes 10 and 11 are moved relatively toward each otherto predetermined positions, regardless of the positions of the'cranes relative to the conductor 65, the resistance of thetwo parallel circuits, carried in part respectively by the cranes, will be varied so as to de-energize the coil 8 and permit the switch 6 to open and stopthe cranes and prevent their colli- ,sion. The cranes canbe' caused to stop at any predeterminedposition apart by raising or lowering the voltage supplied to the 2:

are employed for handling automobile bodies i and chassis. For instance, the crane 10 may be a chassis crane operating to lift and convey a chassis from one point to another: along the crane 11 may be a body crane for conveying same assembly line, the paths'of travel of the body and chassis cranes overlapping. Thus, it frequently happens that one .crane will overrunthe other, resulting in collision and dangerous accid-ents. v vention provides a construction in which one crane can approach the other only a certain predetermined distance, such as a minimum of ten feet.

We claim:

1. In a crane installation having a track adapted to movably support a plurality of cranes, and actuating means for moving said cranes toward and away from one another. the combination therewith of an electrical control for adjacent cranes including an electrically actuated mechanism adapted when the energy supplied thereto-is decreased a predetermined amount to render said actuating means inoperative, and means responsiveto the relative movement of said cranes forvvarying the resistance of said circuit to decrease the energy supplied to said mechanism to render said actuating means inoperative when said cranes move to predetermined relative positions. I I

- 2. In a crane installatlon having a track adapted to movably support a plurality of cranes, and actuating means for moving said cranes toward and away from one another,

bodies on the The present inthe combination therewith of an electrical control circuit for adjacent cranes including an electrically actuated mechanism adapted when the energy supplied thereto is decreased a predetermined amount to render said actuating means inoperative, a source of power for said control circuit, means for maintaining constant the energy supplied to said control circuit, and means responsive to the relative movement of said cranes for varying the resistance of said circuit to decrease the energy supplied to said mechanism to render said actuating means inoperative when said cranes move to predetermined relative positions.

3. In a crane installation having a track adapted to movably support a pair of cranes, and actuating means for moving said cranes toward and away from one another, the combination therewith of an electrical control 7 system for adjacent cranes including a pair of circuits connected in parallel, one of said circuits including mechanism for rendering said actuating means inoperative, and means for varying the relative resistance of said parallel circuits in response to the relative movement of said cranes so as to actuate said mechanism to render said actuating means inoperative when said cranes move to predetermined relative positions.

4. In a crane installation having a track adapted to movably support a pair of cranes, and actuating means for moving said cranes toward and away from one another, the combination therewith of an electrical control system for adjacent cranes including a pair of circuits connected in parallel, one of said circuits including mechanism for rendering said actuating means inoperative, a source of power for said control circuit, means for maintaining constant the energy supplied to said control circuit, and means for varying the relative resistance of said parallel circuits in response to the relative movement of said cranes so as to actuate said mechanism to render said actuating means inoperative when said cranes move to predetermined relative positions.

5. In a crane installation having a track adapted to movably support a pair of cranes and actuating means for moving said cranes toward and away from one another, the combination therewith of an electrical control system for adjacent cranes including a conductor, a pair of contacts engaging said conductor and movable relatively with said cranes, a circuit connected with each of said contacts to provide a pair of circuits connected in parallel to said conductor, electrically actuated mechanism connected in one of said parallel circuits for rendering said actuating means inoperative whereby when said cranes move to predetermined relative positions the relative resistance of said parallel circuits is varied to actuate said mechanism and render said actuating means inoperative.

6. In a crane installation, the combination of a track adapted to movably support a plurality of cranes, actuating means for moving said cranes toward and away from one another, an electrical control for adjacent cranes including electrically actuated mechanism adapted when the energy supplied thereto is decreased a predetermined amount to render said actuating means inoperative, a source of power for said control circuit, and means for varying the energy supplied .to said mecha nism in response to the relative positions of said cranes in such a manner that said actuating means is rendered inoperative when said cranes move to predetermined relative positions.

r In'testimony whereof we aflix our signatures. i

WILLIAM J. KEENAN. GUERDON SATHER. 

